Discrimination between MLOs associated with white leaf diseases of sugarcane and bermuda grass by ELISA and SDS-PAGE

Abstract

Cuttings from sugarcane and bermuda grass plant with white leaf symptoms were collected in Thailand and transferred to a glasshouse at East Malling during 1989-90. Using these plants as source materials, procedures were devised for the partial purification of MLO-associated immunogens. Antisera were raised separately to the sugarcane white leaf (SCWL) and bermuda grass white leaf (BCWL) immunogens. These antisera exhibited specificity for their homologous MLO antigens in F (ab')2 indirect enzyme linked immunosorbent assays (ELISA). No cross reaction was observed in reciprocal tests between these to MLO sources and their antisera. Sodium dodecyl polyacrylamide gel electrophoresis (SDS-PAGE) and-western blotting of SCWL and BGWL antigen preparations revealed a single major protein antigen for each MLO, with molecular weight of 21 kd for SCWL and 19 kd for BGWL. Each MLO antigen reacted only with its homologous antibody. The specificity of the antibody reaction by ELISA, western blotting and the differences in electrophoretic migration of the MLO antigens provide evidence for the separate identities of the MLOs causing the sugarcane and bermuda grass white leaf diseases.